1. Field of the Invention
The present invention generally relates to electrical connectors, and more particularly to an electrical connector having improved electrical characteristics including improved impedance matching, minimized crosstalk and significantly reduced emission and absorption of electromagnetic interference (“EMI”).
2. Description of the Related Art
Electrical connectors are used to place electrical devices, such as printed circuit boards, in electrical communication with one another. Typically, an electrical connector includes a set of electrical contacts that are adapted to receive a first set of pins from the first device to be coupled. The set of contacts extends from the electrical connector and terminates in a second set of pins that connect to the second device to be coupled, placing the two devices in electrical communication with each other through the electrical connector.
In order to minimize high frequency noise, it is desirable to provide a ground plane near the electrical contacts in the electrical connector, the ground plane being connected to ground potential. Typically, one or more of the electrical contacts will be coupled to the ground plane. Known electrical connectors are typically provided with certain predetermined electrical contacts connected to the ground plane. Accordingly, unique electrical connectors must normally be provided for each pair of devices to be interconnected.
The current trend towards miniaturization of electrical devices allows for smaller, faster devices with increased memory and decreased cost, but also means a greater number of electrical connections have to be made in a smaller volume to accommodate communications between devices. As the number of electrical connections in a given volume increases, so does the potential for problems such as crosstalk between the connections. In addition, there is a need for impedance matching between electronic components used on the printed circuit boards.
In order to solve the problems with EMI between a connector and adjacent electronic components, a conventional connector has one or two metal planes or shields disposed on outer surfaces of the connector housing or body. These metal shields reduce EMI that the connector emits from being emitted outside of the connector, while also reducing EMI emitted by adjacent electronic components from being transmitted to the connector. In order to improve the performance of the metal shields, some of the connector contacts are electrically connected to the shield on a male connector and thus, connect the PCB to the shield. When such a male connector is mated with a female connector, contacts on the female connector mate to the shield provided on the male connector in order to create an electrical connection between one PCB and the other. The pattern of contacts that is connected to the shield is determined beforehand and is unique to each connector. Thus, this pattern of shielded contacts cannot be easily customized according to a specific application.
In conventional connectors, there are specifically designated shield contacts which are contacts in the connector that are electrically connected to the shield provided on the connector, and there are specifically designated signal contacts that are provided in the connector to carry signals into and out of the connector. These shield contacts and signal contacts are unique to each type of connector and must be specifically designed and arranged for each connector.
Similarly, the shield or metal housing on the outside surfaces of the connector is specific to each type of connector. The shield is specifically formed according to the size of the connector, the number of shield contacts required and the pattern of shielding and shield contacts required.
Thus, for each connector, a different configuration of signal contacts, shield contacts and shields must be manufactured. This greatly increases the cost and difficulty of connector manufacturing.
In addition, other conventional devices have utilized a ground plane, such as a center plane, disposed between adjacent rows of contacts of a connector, to prevent adjacent rows of pins or contacts from interfering with each other, thereby reducing crosstalk and improving impedance control. More intricate arrangements of such ground planes or shields have also been proposed.
For example, one method of providing shielding for an electrical connector is discussed in U.S. Pat. No. 5,620,340. The '340 patent discloses the use of arrays of square-wave shaped shield plates to form rectangular boxes around groups of electrical contact pins to shield them from other, neighboring pins. While the shielding configuration of this patent reduces crosstalk, it is difficult and expensive to mass produce connectors using the square-wave shaped shielding pieces, since it is difficult to maintain proper alignment of a large number shielding pieces having such a complex shape.
In addition, U.S. Pat. No. 6,299,481 discloses a shielded connector having a shield cover that is substantially U-shaped and is arranged to cover an upper surface, a lower surface and a front surface of an insulative connector housing and electrical contacts or terminals disposed therein. However, this arrangement also suffers from the problems described above.